Comparison of measurement techniques for electron spin relaxation time in a GaAs/AlGaAs multiple quantum well

We compared the performance of three measurement techniques for electron spin relaxation time, i.e., polarization- and time-resolved photoluminescence (PTRPL) measurement, time-resolved reflectance (TRR) measurement, and time-resolved Kerr rotation measurement. With all three techniques similar electron spin relaxation times (0.83–1.2 ns) were obtained in a (110) GaAs/AlGaAs multiple quantum well with excitation wavelengths near the heavy-hole exciton resonance at 77 K. We extracted the spin-independent contribution of the Coulomb interaction which obscures TRR signals as an offset without limiting the excitation wavelength to heavy-hole exciton resonance, using the degree of electron spin polarization simultaneously obtained by the PTRPL measurement. It was found that the Coulomb interaction contribution is dominant in TRR signals over both heavy- and light-hole exciton resonances.